Emulsions of asphalt, bitumen and coal tar have a wide range of uses including binders for roads, water barriers for sub-surface foundations of a building, and saturants for webs such as glass or polyester to make water proof webs which may be cut into shingles. In many of these applications it is desired to cause the emulsion of asphalt, bitumen or coal tar to destablize so that the asphalt, bitumen or coal tar sets and does not flow. This is particularly important in highway construction where the highway is closed until the asphalt, bitumen or coal tar emulsion is set to prevent damage and accidents which may be caused by stones or unbroken emulsion thrown up by traffic. One particular concern is the potential for breaking car windshields.
It is also desired to improve the water resistance of materials made from such emulsions of asphalt, bitumen and coal tar. This is particularly important in roofing applications.
There are a number of references which teach that emulsions of asphalt, bitumen or coal tar may be gelled or set using alkali metal silicofluorides. This art is represented by Chemical Abstract 91:8832 of Czech Pat. No. 176,308 issued Feb. 15, 1979; Chemical Abstract No. 96:39864S of Japanese Pat. No. 39,352 issued Sept. 12, 1981; Chemical Abstract No. 96:163961 of E.P. Application No. 45,619 published Feb. 10, 1982; and Chemical Abstract No. 81:171549n of German Offen. No. 2,363,085 published July 4, 1974.
Unfortunately, asphalt emulsions have a very narrow tolerance to alkali metal silicofluorides. Thus, the silicofluoride must be provided within a very precise limit. If too little is provided, the emulsion will destablize too slowly; and if too much is used, the emulsion will set too fast. This will not permit the emulsions to be worked. There is a need to develop a system which provides a greater tolerance to destabilization of asphalt, bitumen and or tar emulsions.
Additionally, the silicofluoride agents are time delay gelling agents. That is, the agent will cause the emulsion to destablize a relatively short time after the silicofluoride is added to the asphalt emulsion. Generally the silicofluoride must be post added to the emulsion. There is a need for a new type of destabilizer which provides for a longer pot life.
The present invention seeks to address these problems.